Create pre-frozen change records for Object.observe

src/object-observe.js

Index: src/object-observe.js
diff --git a/src/object-observe.js b/src/object-observe.js
index b35f547eda0b89f5a1530e39d552f8f86b55e601..e4a68759e6fc05654d79938023f2800d318f27bc 100644
--- a/src/object-observe.js
+++ b/src/object-observe.js
@@ -130,12 +130,8 @@ function EnqueueChangeRecord(changeRecord, observers) {
   }
 }
 
-function NotifyChange(type, object, name, oldValue) {
-  var objectInfo = objectInfoMap.get(object);
-  var changeRecord = (arguments.length < 4) ?
-      { type: type, object: object, name: name } :
-      { type: type, object: object, name: name, oldValue: oldValue };
-  ObjectFreeze(changeRecord);
+function NotifyChange(changeRecord) {
+  var objectInfo = objectInfoMap.get(changeRecord.object);
   EnqueueChangeRecord(changeRecord, objectInfo.changeObservers);
 }